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Eiro is a moon orbiting Chi Rho, a planet in the Ectanus 45 system. The moon is tidally-locked, give it a light side and dark side comparable with Earth's moon, Luna. This dark side is very cold, and only its equator ceven barely support human life, with temperatures dropping to -35'C even a few kilometers north or south of the equator.[1]


A small settlement was established after the Human-Covenant War.[1]


  1. 1.0 1.1 Halo: Smoke and Shadow, Chapters 1-2